Dillon 308 die question ? using a headspace gauge ?

The directions say to use a chamber headspace gauge to set up the sizing die. Which gauge should be used ? A go gauge, no-go, or field ? Setting it up for a M118LR 308 sniper round if it makes any difference.

The Go, No-Go, and Field gauges are to check to see if the chamber of your rifle is within specs. What they are talking about in setting up your full length resizing die, is something like the RCBS Precision Mic which measures cartridge headspace . Wilson also sells a gauge that measures cartridge base to shoulder dimensions. These tools help you to set up your resizing die so as to bump your shoulder back the proper amount.

Don

Riss

February 3, 2009, 10:24 PM

Trying to figure it out as I am putting on order in to MidwayUSA tonight. I saw cartridge gauges but am having trouble navigating their site to see exactly what I need. Must be lots of traffic on the net.

Riss

February 3, 2009, 10:32 PM

Found the RCBS Precision Mic 308 Winchester at Midway. It appears that this is the beast which you speak of. Did not see it because of internet slowdown. MidwayUSA site is a usual, SLOW. Extra slow tonight makes searching really difficult. Thanks for the help. Any idea on what dies I should get without killing the bank ? I realize I should get good ones, but some of them are downright outrageous in price.

Would have been much easier if Dillon had a link to that piece on their die page. THANKS, will add it to the list of stuff I have to get from Dillon.

30Cal

February 4, 2009, 12:13 PM

It's not easy to get a numical measurement from the case gages. They're basically Go/NoGo affairs.

I prefer the Hornady comparitor over the case gage and RCBS case mic.

rcmodel

February 4, 2009, 12:21 PM

You can do the exact same thing by using your rifle itself.

Just set the die so you can feel slight resistance when closing the bolt on a sized case.

That's closer to being right for your rifle then using a drop-in case guage set to SAAMI "close enough to fit everything" specs.

rc

snuffy

February 4, 2009, 01:33 PM

My experience with the RCBS case gauge is that you can very accurately measure exactly how much headspace your rifle is set to. RATS! That didn't coem out right!:scrutiny:

Here's how it works. You fire a factory round or a handload you made on new-unfired brass. Then you put that round (s) in the case gauge. it will tell you, in .001 accuracy, exactly what your chamber has for headspace. It tells you where your case shoulder is. Example, my .223 bushy, leaves the cases + .007 longer than minimum headspace for .223.

Then you back your FL sizer off about a full turn from contact with the shell holder. Size a case, measure with the gauge, then keep turning the die down until you see the headspace begun to go under where the chamber left it. I've been getting away with setting the shoulder back .003 to end up at .004, they function well in my AR.

For a bolt rifle, you could go with less than .003, camming action being what chambers the round.

The dillon gauge and others like it, only show minimum-maximum headspace via the step cut on the top. They do NOT give a read-out in .000 inch.

243winxb

February 4, 2009, 02:16 PM

+1 You can do the exact same thing by using your rifle itself.

Just set the die so you can feel slight resistance when closing the bolt on a sized case.

That's closer to being right for your rifle then using a DROP-IN CASE GAGE set to SAAMI "close enough to fit everything" specs. This works fine for bolt actions. Your not going to shoot the reloads out of the DROP-IN CASE GAGE are you?

snuffy

February 4, 2009, 03:27 PM

This works fine. Your not going to shoot the reloads out of the gage are you?

Sure it does.

Use the RCBS gauge only if you really want to KNOW what your FL die is doing to your brass. The other ways are pure guess work.

dirtman

February 4, 2009, 04:18 PM

+1 Here's how it works. You fire a factory round or a handload you made on new-unfired brass. Then you put that round (s) in the case gauge. it will tell you, in .001 accuracy, exactly what your chamber has for headspace. It tells you where your case shoulder is. Example, my .223 bushy, leaves the cases + .007 longer than minimum headspace for .223.

I would think you could do it either way, but for me i perfer the RCBS Precision Mic as i can see exactly what i am doing...

Riss

February 4, 2009, 04:29 PM

I understand what measuring a fired case will show me as to what the rifle chamber is. What threw me off was Dillon saying to use a gauge to set up the dies in the first place. Gotta figure if I am going to use all Dillon dies or use Redding or something else. Will be setting up for the same bullet and not changing as the rifle is being chambered for a specific round.

243winxb

February 4, 2009, 06:04 PM

Dillon shell plates may not give you the correct cartridge headspacing if you have the flrs die touching the shell plate fully. Its possible to push the shoulder back to far causing excessive headspace

30Cal

February 4, 2009, 06:12 PM

What threw me off was Dillon saying to use a gauge to set up the dies in the first place.

Here's the deal. There's a certain amount of tolerance to both the shell holder (shell plate) and the die. Combine that with the fact that it takes roughly a 1/16 turn to get a sizable difference in case lengths. If you follow the blind instructions, you've got a good chance of being out of the ballpark.

I used the chamber to set a die for my M1A; set it up so that the bolt just barely closed. Ended up tearing case heads off three firings later. I got a gage and lo-and-behold, I was pushing the shoulder back too far.

The rifle's chamber will tell you if it'll chamber. It won't tell you if you'll be overworking your brass or otherwise creating an excessive headspace condition. A case gage/comparitor/case mic will.

USSR

February 4, 2009, 06:55 PM

The rifle's chamber will tell you if it'll chamber. It won't tell you if you'll be overworking your brass or otherwise creating an excessive headspace condition. A case gage/comparitor/case mic will.

The gauges you mention in your post are for measuring the headspace on you rifle, not your case dimnsions. The go means your rifle chamber is cut to the correct size, if the no go fits your rifle has excessive headspace, the field means that your headspace is ok, but is at the very maximum headspace.

243winxb

February 4, 2009, 11:07 PM

Here is a shell plate that measures .116" If you adjust your FLRS die by the normal method, die kissing the plate, you will have excessive cartridge headspace with you bottle neck brass (223) The correct measurement should be .125" as the RCBS shell holder is. A RCBS Precision Mic or Hornady Comparitor is needed. The drop-in type is less usefull IMO to gage small amounts as little as .003" . SO AS DILLON HAS SAID IN THERE INSTRUCTION, BUY A CARTRIDGE CASE GAGE. Better yet, get the Mic or Comparitor. http://i338.photobucket.com/albums/n420/joe1944usa/IMG_2896A.jpg http://i338.photobucket.com/albums/n420/joe1944usa/IMG_2902DILL.jpg

Walkalong

February 5, 2009, 07:54 AM

On that progressive shellplate you should not be jamming the die down on it, but you are right about single shellholders, and they do vary a bit due to manufactoring tolerances. :)

243winxb

February 5, 2009, 08:49 AM

Use a chamber headspace gauge to set up the sizing die for bottle neck type cases or better still, use a RCBS Precision Mic or Hornady Comparitor. http://i338.photobucket.com/albums/n420/joe1944usa/IMG_2905DILL1.jpg

SlamFire1

February 5, 2009, 09:44 AM

This is the gage I use. Cost about $12.00.

As you can see, new in the package Win brass drops right to the "GO" level on the gage.

This gage is so simple to use. Size your brass, drop it in the gage, and see if it is between the "Go" and "no go".

Showed a gage this week to a new shooter. He was wanting to learn how to reload. He ran his finger over the lip between the go and no go and said something to the effect "that's not much".

The difference between the levels is .006". What's that, less than a fingernail in thickness?

Why horse around guessing?, get a case gage and measure what you are doing!

Why horse around guessing?, get a case gage and measure what you are doing!

I'm glad someone put a pic of one of the solid type case gauges. But the point I've been trying to make is; you're only going to be able to "SEE" major differences with that type of gauge. As far as actual measurements in thousandths of an inch, there are none. If what they show you is good enough, then so be it.

A trip to the range for an informal target game resulted in a fellow shooter and good friend having case head separations plaguing him with several AR .223 rifles. A check with my FA gauge, (didn't have my RCBS mic yet), showed he was pushing the shoulders back too far on all the shells he had loaded for that match. They were way below the "go" line, but how much? .010-.015, my eye is not calibrated that finely. He borrowed that gauge, set his dies so he ended up between go and no-go, had no further problems with his .223 handloads.

Riss

February 5, 2009, 12:53 PM

Yes I know what a go/no-go gauge is. I have several and use them. Was thrown off by Dillon saying to use a gauge to set up the dies. Makes it sound like you put the gauge IN the press to set it up. I have a case gauge, and dies on the way. Will be resurrecting the thread if I have questions setting up the dies.

Riss

February 10, 2009, 02:42 AM

Got the RCBS precision mic and now understand. Not sure if it is "the gauge" that Dillon suggests to use. Since they don't say "get this one". BUT, it will do the job, and very well I do believe. Forgot to also get a chamber checker gauge. Oh well, save that for next weeks order.

243winxb

February 10, 2009, 07:58 AM

Use a "CARTRIDGE" headspace gauge to set up the sizing die for bottle neck type cases or better still, use a RCBS Precision Mic or Hornady Comparitor. (The edit button is missing.)

Welding Rod

April 5, 2012, 01:20 PM

+1 Here's how it works. You fire a factory round or a handload you made on new-unfired brass. Then you put that round (s) in the case gauge. it will tell you, in .001 accuracy, exactly what your chamber has for headspace. It tells you where your case shoulder is. Example, my .223 bushy, leaves the cases + .007 longer than minimum headspace for .223.

I would think you could do it either way, but for me i perfer the RCBS Precision Mic as i can see exactly what i am doing...

I know this is an old thread but I am replying as I see this practice as unsafe.

When brass is extracted from an auto loader its post-fired headspace length can be longer than the chamber dimension. I would never use this dimension as a reference for setting sizing dies for an auto loader as the headspace dimension on your reloads could then be too long.

My M1A's brass measures quite a bit longer than the measured headspace dimension of the chamber (using a RCBS Precision Mic to compare the lengths of both the headspace gauge and the fired brass).

The way to measure headspace is with a set of headspace gauges.

Jdillon

April 5, 2012, 11:24 PM

I use several different tools to set up my FL sizing dies including; Hornady, Innovative Technologies, RCBS Precision Mic as well as Wilson and Dillon case gauges. For my gas guns, I found the RCBS Precision Mic works best on fired cases due to irregularities in the shoulder of fired cases. I setup my Dillon 550B with the RCBS Mic to achieve a "bump" of approximately .003" on .223 cases. I run a number of test cases (10-12) through the sizing die after final adjustment to verify consistent sizing. Although somewhat time consuming, it takes the guess work out of setting up your dies.

Case gauges are fine but but will not give you the same level of precision as using the other tools mentioned. On bolt or single shot rifles, the IT, Hornady and RCBS all work very well.

Walkalong

April 6, 2012, 07:41 AM

I use a case gauge like Slamfire1 showed to check cases sized for autos. I use other methods to size for a gun when I do not expect to fire it in any but my gun. If you use a case gauge for that as well, it will ensure proper headspace in any gun with a properly installed barrel with a properly machined chamber. It eliminates measurement errors as well. Stick the case in and look at it. Very simple.